Enhanced protection against tuberculosis by vaccination with recombinant BCG over-expressing HspX protein

Immunization with Mycobacterium bovis Bacille Calmette–Guerin (BCG) did not induce adequate Th1 responses to the latency antigen, HspX of M. tuberculosis. To increase the immunogenicity and protective efficacy of BCG, a recombinant BCG strain over-expressing antigen HspX (rBCG::X) was constructed. The recombinant strain rBCG::X expressed high levels of both HspX protein in the cytosol and Ag85B protein in the cytosol and supernatant. Mice vaccinated with rBCG::X produced a more consistent and enduring protective effect against infection with M. tuberculosis, showing lower bacterial load in lung and less severe lung pathology, than the control mice vaccinated with BCG strain containing the vector pMV261. The long-term protection induced by rBCG::X was associated with significant increases in antigen-specific IFN-γ to both HspX and Ag85B proteins, while PPD-specific IFN-γ responses declined. Our results suggest that latency antigens of M. tuberculosis may be promising targets for developing more effective recombinant BCG strains to protect against TB.     

广州市新生儿卡介苗接种质量监测

目的　了解 2 0 0 1～ 2 0 0 3年广州市新生儿卡介苗接种质量。方法　对 2 0 0 1～ 2 0 0 3年广州市越秀、荔湾、东山、海珠区 2 4个接种单位的新生儿卡介苗接种报表和质量监测结果进行分析。结果　新生儿卡介苗接种率、接种后1 2周结核菌素纯蛋白衍化物 (TB -PPD)阳转率、PPD反应平均直径、卡痕率、卡痕平均直径等指标均较稳定。结论　广州市新生儿卡介苗接种工作质量较高并保持稳定。     

Drug treatment combined with BCG vaccination reduces disease reactivation in guinea pigs infected with Mycobacterium tuberculosis

Bacillus-Calmette-Guerin (BCG), the only human tuberculosis vaccine, primes a partially protective immune response against Mycobacterium tuberculosis infection in humans and animals. In guinea pigs, BCG vaccination slows the progression of disease and reduces the severity of necrotic granulomas, which harbor a population of drug-tolerant bacilli. The objective of this study was to determine if reducing disease severity by BCG vaccination of guinea pigs prior to M. tuberculosis challenge enhanced the efficacy of combination drug therapy. At 20 days of infection, treatment of vaccinated and non-vaccinated animals with rifampin, isoniazid, and pyrizinamide (RHZ) was initiated for 4 or 8 weeks. On days 50, 80 and 190 of infection (10 weeks after drug were withdrawn), treatment efficacy was evaluated by quantifying clinical condition, bacterial loads, lesion severity, and dynamic changes in peripheral blood and lung leukocyte numbers by flow cytometry. In a separate, long-term survival study, treatment efficacy was evaluated by determining disease reactivation frequency post-mortem. BCG vaccination alone delayed pulmonary and extra-pulmonary disease progression, but failed to prevent dissemination of bacilli and the formation of necrotic granulomas. Drug therapy either alone or in combination with BCG, was more effective at lessening clinical disease and lesion severity compared to control animals or those receiving BCG alone. Fewer residual lesions in BCG vaccinated and drug treated animals, equated to a reduced frequency of reactivation disease and improvement in survival even out to 500 days of infection. The combining of BCG vaccination and drug therapy was more effective at resolving granulomas such that fewer animals had evidence of residual infection and thus less reactivation disease.     

2007—2010年青海省达日县结核病监测分析

目的分析2007—2010年青海南部牧业区达日县结核病疫情,为进一步防治结核病和结核病控制项目的实施提供依据。方法收集整理4年结核病人的监测资料,进行统计分析。结果 4年共发现结核病人241例,男、女性发病人数分别占60.58%、39.42%。以20～40岁发病比例最高,10岁以下年龄组的发病比例较低。职业中以牧民最高,为83.81%;其次是学生,为10.41%。4年涂阳肺结核分别为23.33%,43.48%,50.0%,53.57%,呈逐年上升趋势。涂阳病人的治愈率由2007年的85.71%上升到2010年的93.33%。结论达日县结核病控制项目的实施使结核病人的诊治和该病的预防控制得到了保证,监测表明,仍需加大对该病防治的投入,以进一步达到控制结核病目标。     

宁波市肺结核病药物耐药监测报告

目的 建立以WHO指南为基础的结核病细菌学耐药监测系统，掌握宁波市初始和获得性耐药水平。方法 采用整群抽样方法于1999年10月至2000年3月选择全市所有新发涂阳病例（包括复治涂阳病例），并对其全部培养阳性的菌株进行菌型鉴定及4种抗结核药物（INH，SM、RFP、EMB）的耐药测试。结果 总耐药率为22.44%，初始耐药率为17.87%，初始耐多药率为3.40%。获得性耐药率为78.95%。获得性耐多药率为42.11%。结论 宁波市结核病的初始耐药率处于较高水平，须进一步加强全市的结核病控制工作。     

BCG vaccination-induced long-lasting control of Mycobacterium tuberculosis correlates with the accumulation of a novel population of CD4+IL-17+TNF+IL-2+ T cells

Mycobacterium bovis Bacille Calmette-Guerin (BCG) is the only vaccine in use to prevent Mycobacterium tuberculosis (Mtb) infection. Here we analyzed the protective efficacy of BCG against Mtb challenges 21 or 120 days after vaccination. Only after 120 days post-vaccination were mice able to efficiently induce early Mtb growth arrest and maintain long-lasting control of Mtb. This protection correlated with the accumulation of CD4⁺ T cells expressing IL-17⁺TNF⁺IL-2⁺. In contrast, mice challenged with Mtb 21 days after BCG vaccination exhibited only a mild and transient protection, associated with the accumulation of CD4⁺ T cells that were mostly IFN-γ⁺TNF⁺ and to a lesser extent IFN-γ⁺TNF⁺IL-2⁺. These data suggest that the memory response generated by BCG vaccination is functionally distinct depending upon the temporal proximity to BCG vaccination. Understanding how these responses are generated and maintained is critical for the development of novel vaccination strategies against tuberculosis.     

The impact of a change in infant BCG vaccination policy on adolescent TB incidence rates: A South African population-level cohort study

ObjectiveSouth Africa’s infant Bacille Calmette Guerin (BCG) vaccine policy changed from percutaneous (PC) BCG Japan to intradermal (ID) BCG Denmark in 2000. This study investigated whether this change in infant BCG vaccination had any durable impact on TB incidence rates (IR) into adolescence.MethodsThe Cape Town electronic TB register provided data (from 2008 to 2018) on HIV-negative TB patients born in 1991–1999 (BCG Japan cohort) and 2001–2008 (BCG Denmark cohort). Statistics South Africa provided population estimates. Annual TB IR per 100,000 population were calculated stratified by age, gender and birth year. Interrupted time series analysis with a segmented Poisson regression and birth cohort analyses were used to compare incidence between the BCG cohorts and trends over time.FindingsTB IR increased throughout adolescence, with 17-year-olds having 7.34 [95% confidence interval (CI), 6.48–8.32] times higher TB IR than 10-year-olds. Females had 1.22 [95% CI 1.17–1.27] higher IR than males. Overall, adolescents who received ID BCG Denmark had a lower TB IR compared to PC BCG Japan (rate ratio 0.86, [95% CI 0.80–0.94]). No interaction between BCG and age, nor BCG and gender were identified. Birth cohort analyses showed the increase in TB IR started around one year earlier in females than in males.ConclusionThe change in infant BCG policy was associated with a modest decrease in TB incidence in 10- to 17-year-old HIV-negative adolescents. However, TB incidence rapidly increased with age in both adolescent cohorts and remained high despite BCG vaccination at birth.     

Oral vaccination of badgers (Meles meles) with BCG and protective immunity against endobronchial challenge with Mycobacterium bovis

Eurasian badgers (Meles meles) are a reservoir host of Mycobacterium bovis and are implicated in the transmission of tuberculosis to cattle in Ireland and Great Britain. The development of a vaccine for use in badgers is considered a key element of any long-term sustainable campaign to eradicate the disease from livestock in both countries. The aim of this study was to investigate the protective response of badgers vaccinated orally with Bacille Calmette–Guérin (BCG) encapsulated in a lipid formulation, followed by experimental challenge with M. bovis. A group of badgers was vaccinated by inoculating the BCG–lipid mixture containing approximately 10⁸ colony forming units (cfu) of BCG into the oesophagus. The control group was sham inoculated with the lipid formulation only. Thirteen weeks after vaccination all the badgers were challenged with approximately 10⁴ cfu of M. bovis delivered by endobronchial inoculation. Blood samples were taken throughout the study and the cell mediated immune (CMI) responses in peripheral blood were monitored by the IFN-γ ELISA and ELISPOT assay. At 17 weeks after infection all the badgers were examined post-mortem to assess the pathological and bacteriological responses to challenge. All badgers in both groups were found to be infected. However, a significant protective effect of BCG vaccination was measured as a decrease in the number and severity of gross lesions, lower bacterial load in the lungs, and fewer sites of infection. The analysis of immune responses showed that vaccination with BCG did not generate any detectable CMI immunological responses, however the levels of the responses increased in both groups following M. bovis infection. The results of the study showed that vaccination with oral BCG in the lipid formulation generated a protective effect in the badgers.     

宣城市500名婴儿卡介苗接种效果评价

目的评价分析宣城市卡介苗接种效果,探讨提高卡介苗接种工作质量的相关方法。方法 2007～2009年、2011年期间随机抽取宣城市10个接种点的500名1岁以内健康婴儿,在接种卡介苗12w后,测量卡痕径值及进行BCG-PPD阳转试验。结果 500名婴儿的卡痕率为97.40%,结核菌素试验阳转率87.80%;不同性别、城乡接种点的婴儿结核菌素试验阳性率差异无统计学意义(P值均小于0.05);不同接种月龄婴儿间结核菌素试验阳性率无统计学差异(χ2=0.55,P=0.76)。卡痕径值≥4mm的婴儿结核菌素试验阳性率高于卡痕径值4mm的婴儿。结论宣城市卡介苗接种卡痕率、阳转率达到国家免疫规划要求,接种质量比较稳定。新生儿出生1个月后、3个月内接种卡介苗,对接种质量无明显影响。卡痕径值大小,对评价接种质量具有一定参考意义。     

Lower incidence of hospital-treated infections in infants under 3 months of age vaccinated with BCG

BackgroundLive vaccines potentially have non-specific effects that protect against other infections than those the vaccines are targeted against. The national vaccination program (NVP) in Finland was changed on September 1st, 2006: before BCG vaccine was given to all newborn babies and afterwards to babies in risk groups only. We used this natural experiment to study the non-specific effects of BCG in the frame of NVP using before-after design.MethodsWe compared the incidence of several outcomes obtained from Finnish health registers between children born between July 1st, 2004, and June 30th, 2006 (BCG-eligible) and an age- and season-matched reference cohort born between July 1st, 2007, and June 30th, 2009 (BCG-non-eligible) using Poisson regression. These cohorts were restricted to full-term children whose parents were born in Finland. Follow-up began at birth and lasted 3 months, which is the scheduled age for DTaP-IPV-Hib vaccination, and from 4 months until first birthday. The outcomes included all infections, pneumonia and injuries as a negative control outcome.ResultsThe incidence rate ratio (IRR) of the BCG-eligible cohort (N = 93,658) compared to BCG-non-eligible cohort (N = 94,712) for hospital-diagnosed infections was 0.89 (95 %Cl 0.86–0.93) for the 3-month follow-up. The decrease was mainly caused by respiratory infections. In 4–12 months follow-up the BCG-eligible had slightly more infections than BCG-non-eligible children (IRR 1.03, 1.01–1.06).ConclusionsBCG vaccination was associated with a lower incidence of all hospital-diagnosed infections during the first three months of life. The difference cannot be attributed to lung tuberculosis, since only few paediatric cases occurred in Finland during 2000s. The disappearance of non-specific effect after administration of an inactivated vaccine is compatible with previous studies.     

Improved long-term protection against Mycobacterium tuberculosis Beijing/W in mice after intra-dermal inoculation of recombinant BCG expressing latency associated antigens

Bacille Calmette-Guérin (BCG) is the vaccine against tuberculosis (TB), but has varied efficacy in different geographical locations. Recombinant strategies to genetically modify the organism to enhance the quality of the immune response have aimed at improving BCG efficacy. Here we describe such a strategy using rBCGΔureC∷hly expressing defined latency-associated antigens and test this construct for long-term protection against an isolate of the Mycobacterium tuberculosis (Mtb) Beijing/W lineage. Expression of the antigens Rv2659c, Rv3407 and Rv1733c by rBCGΔureC∷hly improved long-term efficacy in both lung and spleen at day 200 post-infection after intradermal vaccination of mice. Our data support expression of Mtb latency associated antigens by rBCG to improve protection against Mtb.     

Novel vaccine prime and selective BCG boost: A new tuberculosis vaccine strategy for infants of HIV-infected mothers

Novel tuberculosis vaccination strategies hinge on BCG priming, yet newborn BCG vaccination may cause BCG disease in HIV-infected infants. Viral-vectored or subunit prime vaccine, followed by delayed BCG boost only for HIV-uninfected infants, may be a safe alternative for all newborns, regardless of maternal HIV infection. This approach should be tested using new tuberculosis vaccine candidates. If safety and immunogenicity of a novel vaccine prime is established in infants of HIV-infected mothers, for whom newborn BCG carries unacceptable risk, this strategy might then be compared to conventional BCG prime and viral-vectored or subunit boost, and BCG alone, in HIV-unexposed infants.     

The effect of high-dose vitamin A supplementation administered with BCG vaccine at birth may be modified by subsequent DTP vaccination

Unexpectedly, we found no overall beneficial effect on mortality in a randomised trial of vitamin A supplementation (VAS) or placebo administered with BCG vaccine at birth in Guinea-Bissau. We conducted an explorative analysis to examine whether subsequent diphtheria–tetanus–pertussis (DTP) vaccinations had modified the effect of VAS at birth. VAS was associated with a weak tendency for decreased mortality as long as BCG was the most recent vaccination, the mortality rate ratio being 0.86 (0.48–1.54); 0.82 (0.32–2.08) in girls and 0.89 (0.43–1.88) in boys. However, after DTP vaccination VAS at birth was associated with increased mortality in girls (2.19 (1.09–4.38)), whereas no difference was seen for boys (0.90 (0.44–1.82)) (p = 0.08 for equal effect of VAS in the two sexes if DTP is the last vaccine). The explanation for the lack of beneficial effect in our setting may have been that VAS at birth interacted negatively with subsequent DTP vaccinations in girls.     

BCG sub-strains induce variable protection against virulent pulmonary Mycobacterium tuberculosis infection, with the capacity to drive Th2 immunity

The hallmark of a vaccine is to induce long-term protective immunity against the pathogen. The use of Mycobacterium bovis BCG as a vaccine against tuberculosis has been problematic in that immunity induced by BCG wanes over time and it may be less effective against more virulent strains of Mycobacterium tuberculosis. Thus it is important to determine what factors might be associated with waning or inefficient immunity. One such factor has been associated with the difference in many types of BCG that are used around the world, or more specifically due to the loss of genomic material in the various sub-strains used in vaccination programs. To address this issue we investigated the long-term immune response generated by 3 sub-strains BCG in the C57BL/6 mouse model of experimental tuberculosis. Mice vaccinated with these diverse strains of BCG were assessed at 6 and 12 months post-vaccination. All BCG sub-strain induced elevated levels of IFN-γ-producing cells at each time point as determined by ELISpot assay. However, when mice were challenged at 6 and 12 months with either M. tuberculosis H37Rv or HN878 the ability of the BCG sub-strains to protect vaccinated mice varied, depending on the time of challenge and on the strain used to infect mice. BCG Pasteur was then used to vaccinate guinea pigs, which were subsequently infected with either H37Rv or HN878. Data showed that BCG Pasteur prolonged the survival of guinea pigs against infection with both strains. Taken together these data suggest that longevity of the immune response generated by BCG is not related to the loss of genetic material and that BCG can induce a protective immune response to infection with a clinical strain of M. tuberculosis.     

Evidence of an effect of BCG revaccination on incidence of tuberculosis in school-aged children in Brazil: second report of the BCG-REVAC cluster-randomised trial

BCG revaccination is still used in some tuberculosis endemic countries. Until now, the little evidence available suggested that BCG revaccination confers very limited additional protection, although there was no information on whether protection depends on the setting and age of revaccination, or if protection increases with time since vaccination. Here we report on an extended follow up of the BCG-REVAC trial, a cluster randomised trial conducted in the Brazilian cities Salvador and Manaus including over 200,000 children aged 7-14 years aimed to evaluate the efficacy of BCG revaccination in children who had received neonatal BCG vaccination. With the extended follow-up (9 years) and the additional cases accrued we now have enough power to report vaccine efficacy separately for the two cities (with different distances from Equator and presumably different prevalence of non-tuberculosis mycobacteria), and by age at vaccination and clinical form. The overall vaccine efficacy was 12% (−2 to 24%) as compared to 9% (−16 to 29%) for the 5-year follow up. Vaccine efficacy was higher in Salvador (19%, 3 to 33%) than in Manaus (1%, −27 to 27%) with the highest vaccine efficacy in children from Salvador aged <11 years at revaccination (33%, 3 to 54%). The findings are in line with the hypothesis that BCG vaccination offers higher efficacy in low NTMb prevalence, and show that revaccination with BCG can offer weak protection in selected subgroups.     

Oral delivery of BCG Moreau Rio de Janeiro gives equivalent protection against tuberculosis but with reduced pathology compared to parenteral BCG Danish vaccination

There is a need for an improved vaccine to better control human tuberculosis (TB), as the only currently available TB vaccine, bacillus Calmette–Guerin (BCG) delivered parenterally, offers variable levels of efficacy. Therefore, recombinant strains expressing additional antigens are being developed alongside alternative routes to parenteral delivery. There is strong evidence that BCG Moreau (RdJ) is a safe and effective vaccine in humans when given by the oral route. This study compared the efficacy of a single oral dose of wild type BCG Moreau Rio de Janeiro (RdJ), or a recombinant RdJ strain expressing Ag85B-ESAT6 fusion protein, formulated with and without lipid to enhance oral delivery, with subcutaneous BCG Danish 1331 and saline control groups in a guinea pig aerosol infection model of pulmonary tuberculosis. Protection was measured as survival at 30 weeks post-challenge and reduced bacterial load and histopathology in lungs and spleen. Results showed that a single oral dose of BCG Moreau (RdJ) or recombinant BCG Moreau (RdJ)-Ag85B-ESAT6, formulated with or without lipid, gave protection equivalent to subcutaneously delivered BCG Danish in the 30 weeks post-challenge survival study. The orally delivered vaccines gave reduced pathology scores in the lungs (three of the four formulations) and spleens (all four formulations) compared to subcutaneously delivered BCG Danish. The oral wild type BCG Moreau (RdJ) in lipid and the unformulated oral wild type BCG Moreau (RdJ) vaccine also gave statistically lower bacterial loads in the lungs and spleens, respectively, compared to subcutaneously delivered BCG Danish. This study provides further evidence to show that lipid formulation does not impair vaccine efficacy and may enhance the delivery and stability of oral vaccines intended for use in countries with poor health infrastructure. Oral delivery also avoids needles (and associated cross-infection risks) and immunisation without the need for specially trained medical professional staff.     

Comparative performance of public and private sector delivery of BCG vaccination: Evidence from Sub-Saharan Africa

Background

The private sector is an important source of health care in the developing world. However, there is limited evidence on how private providers compare to public providers, particularly for preventive services such as immunizations. We used data from Sub-Saharan Africa (SSA) to assess public–private differences in Bacillus Calmette–Guérin (BCG) vaccine delivery.

Methods and findings

We used demographic and health surveys from 102,629 children aged 0–59 months from 29 countries across SSA to measure differences in BCG status for children born at private versus public health facilities (BCG is recommended at birth). We used a probit model to estimate public–private differences in BCG delivery, while controlling for key confounders. Next, we estimated how differences in BCG status evolved over time for children born at private versus public facilities. Finally, we estimated heterogeneity in public–private differences based on wealth and rural–urban residency. We found that children born at a private facility were 7.1 percentage points less likely to receive BCG vaccine in the same month as birth than children born at a public facility (95% CI 6.3–8.0; p < 0.001). Most of this difference was driven by for-profit private providers (as opposed to NGOs) where the BCG provision rate was 10.0 percentage points less than public providers (95% CI 9.0–11.2; p < 0.001) compared to only 2.4 percentage points for NGOs (95% CI 1.0–3. 8; p < 0.01). Moreover, children born at private for-profit facilities remained less likely to be vaccinated up to 59 months after birth. Finally, public–private differences were more pronounced for poorer children and children in rural areas.

Conclusions

The for-profit private sector performed substantially worse than the public sector in providing BCG vaccine to newborns, resulting in a longer duration of vulnerability to tuberculosis. This disparity was greater for poorer children and children in rural areas.     

Prospective study of smoking and tuberculosis in India

OBJECTIVE: Although tuberculosis has already become uncommon in industrialised countries, is a major burden in many developing countries, including India. This paper examines the association between smoking (mainly bidi smoking) and tuberculosis in Mumbai, India. METHOD: To study the possible association between smoking and tuberculosis, recruitment of a cohort of 81,443 men > or =35 years began in 1991 and was followed up to the end of 2003 in Mumbai. RESULTS: The adjusted risk of tuberculosis deaths among bidi smokers was 2.60 (95% confidence interval (CI): 2.02, 3.33) times higher than never-smokers, with a significant trend for daily frequency of bidi smoking. Also the risk of prevalence of self reported tuberculosis among bidi smokers was 5.23 (95% CI: 4.01, 6.82) times higher than never-smokers. CONCLUSION: In India around 32% of tuberculosis deaths can be attributable to bidi smoking. Thus, bidi smoking seems to be an important cause of manifestation and death from tuberculosis.